1. Field of the Invention
The invention relates generally to a robot device lift. More particularly, the invention relates to a robot lift or a robot arm that displaces the robot while maintaining the substrate within a series of parallel planes.
2. Description of the Background Art
Substrates such as semiconductor wafers, substrates, or displays such as light emitting diode (LED) displays are processed to produce integrated circuits using a series of processes. These processes are often performed in a variety of process chambers. Other chambers known as metrology chambers are used to measure substrates. An assemblage of process or metrology chambers, or a combination of the two, served by a substrate transport robot in a non-linear configuration is known as a cluster tool. Each robot typically resides in a transfer chamber that is connected to each of the plurality of process chambers such that the robot can access semiconductor substrates in each of the process chambers.
Providing robot designs that can efficiently transfer substrates between, and within, multiple process chambers that are positioned in different orientations and vertical levels improves applicability of the robot over robot designs that are limited to transfer substrates only between process chambers positioned at the same vertical level.
End effectors, also known as robot blades, are configured to support substrates to provide for transfer of the substrates to/from the process cells. Linear motion of end effectors is one of the basic motions associated with robot travel. There are multiple elements that are desired to be linearly displaced in a semiconductor process chamber or cluster tool environment while allowing the end effector to follow a series of parallel planes. For example, robot lifts are provided that vertically displace a plate that a robot is mounted on, to a variety of different vertical positions as the robot is maintained in a substantially horizontal orientation. Load locks are often used to transfer semiconductor substrates between the interior and the exterior of a cluster tool, individual process chamber, or between different segments of a cluster tool. A cassette is integrated into the load lock and contains a plurality of vertically-spaced slots, a substrate can fit in each slot. The cassettes are typically displaced vertically to align different cassette slots with a robot end effector for loading or unloading of the substrates into the cassette slots.
Robot arms are used to linearly extend end effectors in certain applications. Linear adjustment of an end effector in a robot can be accomplished either by the robot linearly displacing its end effector, or by linearly displacing the platform on which the robot is mounted. In load locks, for example, the linear adjustment of the cassette slots can be accomplished by linearly adjusting the entire cassette. The mechanism that linearly adjusts the robot platform can be structurally similar to the mechanism that linearly adjusts the position of the cassette. A telescoping member is commonly used to linearly displace the robot base. Such telescoping members are typically relatively complex and expensive to construct, and suffer from production of a considerable amount of dirt, e.g., oil, grease, metal shavings, a variety of particulate matter, etc. The telescoping member is also likely to become misaligned after extended use due to its inherent structural complexity. In semiconductor applications, precision is very important during the robot transfer of substrates and other objects using robots, robot arms, and load locks. The precision of motion in robot applications often dictates the type of equipment that may be used to produce the robot motion.
Commonly used linear robot extension devices applied to semiconductor applications produce a considerable amount of dirt. Such linear robot extension devices often rely upon linear drive devices. The linear drive devices are configured with a sliding xe2x80x9ccarxe2x80x9d that is constrained to follow a guide, and often uses gears to provide the motion. Such relative mechanical sliding/contacting motion requires an undesirable amount of lubricants to lubricate the contacting surfaces, the lubricants also produce an undesirable amount of dirt. Such dirt is especially undesirable in such a clean environment as semiconductor processing. Further, it is difficult to contain such dirt produced in prior art linear robot extension devices since the linear motor typically has an extended vertical travel path that is necessary to transfer substrates between vertically-spaced semiconductor applications. Accordingly, the extended vertical travel path allows the dirt to become distributed through the system.
Therefore, a need exists in the art for an apparatus or method that can linearly displace a robot and/or a cassette while limiting tilting of the robot/cassette. Such an apparatus or method should be configured to maintain as clean an environment as possible during use.
A method and associated apparatus includes a guide apparatus comprising a plurality of guide linkages. Each one of the plurality of guide linkages comprises a pair of linkage members, each pair of the linkage members are rotatably connected about a guide pivot axis. The guide pivot axis of each guide linkage is arranged in a direction opposed to the direction of the guide pivot axis of the remainder of the guide linkages. In one aspect, each guide linkage is arranged between a robot platform or a cassette and a base such that extending each of the plurality of guide linkages acts to linearly displace the robot platform relative to the base while limiting tilting of the robot platform or the cassette. In another aspect a robot can extend its end effectors while limiting tilting of the end effectors.